The invention relates to a modular jack and, more particularly, to a modular jack which may be compliant with multiple communication standards and/or which includes improved noise compensation abilities.
The use of modular plugs and jacks for data transmission is known. Basically, in order to establish electrical communication and a data path between a first and second device, the first device may send information in the form of electrical signals out into a cable that terminates in a plug. The second device may include a jack. The plug and jack are designed so as to be easily mechanically mate-able in a male-female configuration. Once the plug and jack are mated, electrical members in the plug and connector engage and are electrically mated so that electrical information signals may travel from the first device to the second device.
This plug and jack design is limited by the physical configuration of the modular plug and jack. As data transmission speeds have increased, electrical performance relating to the transfer of electrical signals from plug to connector, has been affected. Each plug and jack frequently includes multiple pairs of contacts used to communicate information. Cross talk between these pairs (where electrical signals in one pair affect electrical signals in another pair) and interference from sources external to the plug-jack configuration, become more of a factor at higher speeds. In order to carry the higher speed data without signal degradation, the plug and connector design changed to include compensation circuitry such as that used to balanced impedance in transmission lines.
Standards organizations such as the Telecommunication Industry Association and the International Organization for Standardization publish standards regarding performance specifications and equipment configurations for plugs and connectors. Different levels or “categories” have been defined for use in twisted-pair cabling such as where a single insulated sheath includes two twisted wires. For example, “Category 6” jacks should be able to handle data communications with a frequency up to 250 MHz. More recent requirements, e.g. Category 7, require jacks which can communicate as high as 600 MHz.
Prior art Category 6 jacks typically employ the compensation circuit near terminals in the jack. That is, a plug having contacts mates with a jack having contacts so that the contacts in the plug physically touch and electrically engage with the contacts in the jack. The electrical signals sent from the contacts of the plug to the contacts of the jack travel through the contact portions of the contacts of the jack to terminals portion of the contacts of the jack and then those terminal portions are connected to a circuit board. The compensation circuit in these prior art Category 6 jacks is typically disposed near the terminal portions. For example, information signals may travel through the terminal portions through the compensation circuit and then to the circuit board. The inventors of the present invention have performed research and learned of the surprising discovery that movement of the compensation circuit to a different location yields significantly better electrical characteristics as is discussed in more detail below.
An example of a prior art jack which may be used for both Category 6 and Category 7 communications is shown in U.S. Pat. No. 6,739,892 and is reproduced in part, in FIG. 1. Referring to FIG. 1, a prior art connector 50 consists of a shield 52, a dielectric housing 54, a switch insert 56 and a circuit board sub-assembly 58. When assembled, sub-assembly 58 is inserted into switch insert 56, switch insert 56 is inserted into housing 54, and housing 54 is inserted into shield 52. When a Category 6 plug is inserted into jack 50, terminals on sub-assembly 58 engage corresponding terminals of the plug for data communication. If a Category 7 plug is inserted into jack 50, a protrusion on the plug (not shown) engages a switch 60 on switch insert 56. Switch 60 causes some of the terminals in connector 50 to be lifted away from electrical connection and moved into contact with a grounding member (not shown).
There are problems with the prior art connector shown in FIG. 1. Requiring a switch to disengage or ground some of the terminals increases the complexity of the device. Moreover, there is the possibility of an open circuit especially if there is a failure in the switch. Finally, any compensation circuitry is disposed from terminal portions of the contacts.